Partially purified homoserine dehydrogenase was prepared from pea seedlings.The optimum pH for this enzyme is approximately 5.4. TheKmvalues for ASA and TPNH are 4.6×l0−4Af and 7.7×l0−5M, respectively. This enzyme can also utilize DPNH but less effectively than TPNH. In contrast with yeast homoserine dehydrogenase which is insensitive to—SH reagents, the pea enzyme is inhibited almost completely by 10−4MPCMB and 10−5MHgCl2, the inhibition being removed by 10−2Mthioglycolate. Homoserine dehydrogenase was found not only in decotylized seedlings, but also in cotyledons.The significance of this enzyme in homoserine biosynthesis in germinating pea seeds has b
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